Flow meter monitoring and data logging system

ABSTRACT

A flow meter monitoring system ( 400 ) is provided according to an embodiment of the invention. The flow meter monitoring system ( 400 ) includes a communication interface ( 401 ) configured to receive flow meter output, a pre-error memory ( 407 ), an error log ( 409 ), and a processing system ( 403 ) configured to communicate with the communication interface ( 401 ), the pre-error memory ( 407 ), and the error log ( 409 ). The processing system ( 403 ) is further configured to capture the flow meter output into the pre-error memory ( 407 ), with the flow meter output overwriting an oldest flow meter output stored in the pre-error memory ( 407 ), detect a predetermined start triggering condition in the flow meter output, transfer a pre-error memory data from the pre-error memory ( 407 ) into the error log ( 409 ) when the predetermined stat triggering condition is detected, and capture the flow meter output into the error log ( 409 ) after the predetermined start triggering condition is detected.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention is related to the field of monitoring a flow meter, and inparticular, capturing flow meter output according to predeterminedtriggering conditions.

2. Statement of the Problem

Flow meters are used to measure the mass flow rate, density, and otherinformation for flowing materials. The flowing materials can includeliquids, gases, combined liquids and gases, solids suspended in liquids,and liquids including gases and suspended solids. For example, flowmeters are widely used in the well production and refining of petroleumand petroleum products. A flow meter can be used to determine wellproduction by measuring a flow rate (i.e., by measuring a mass flowthrough the flow meter), and can even be used to determine the relativeproportions of the gas and liquid components of a flow.

One problem that can occur in the meter output is an erroneous readinggenerated by sudden changes in the material. For example, if a liquid isbeing transferred and bubbles of gas are trapped in the liquid, theresulting large changes in mass flow rate in the flow meter due to thegas bubbles can cause large and inaccurate variations in the meteroutput. Similarly, the meter output can be degraded due to rapid changesin pressure, temperature, flow velocity, etc. Moreover, differentmaterials can react differently to ambient conditions. Therefore, it iscommon for an operator to calibrate or configure a flow meter not onlyaccording to the material being transferred, including percentages ofliquid, solids, and gases in the material, but also according to ambientconditions such as temperature, atmospheric pressure, flow pressure ofthe material, etc.

One prior art approach to monitoring a flow meter output is to detect anerror (such as a large variation in drive gain) and capture meter outputafter the error has occurred. The drawback of this approach is thatalthough the error condition may be captured, the meter events and flowconditions leading up to the error condition are not captured. Anoperator therefore may not be able to determine the cause of theproblem, and remedial action cannot be determined or carried out.

A second prior art approach is to capture all meter output and store itin the event of an error condition. The data will enable an operator toreview and diagnose the meter operation and/or flow conditions that ledto the error. However, this approach also has drawbacks. The storagecapacity needed to continuously and completely monitor a flow meter inoperation would need to be large. The storage capacity needed to monitormultiple flow meters could become prohibitive. The storage capacitytherefore is costly. In addition, the operator time would be expensive,as the operator would have to review large amounts of data in order tofind the pertinent signals that occurred before the error condition.

SUMMARY OF THE SOLUTION

The invention helps solve the above problems with monitoring a flowmeter output.

A method of monitoring a flow meter is provided according to anembodiment of the invention. The method comprises the steps of capturinga flow meter output into a pre-error memory, with the flow meter outputoverwriting an oldest flow meter output stored in the pre-error memory,detecting a predetermined start triggering condition in the flow meteroutput, transferring a pre-error memory data into an error log when thepredetermined start triggering condition is detected, and capturing theflow meter output in the error log after the predetermined starttriggering condition is detected.

A flow meter monitoring system (400) is provided according to anembodiment of the invention. The flow meter monitoring system (400)comprises a communication interface (401) configured to receive flowmeter output, a pre-error memory (407), an error log (409), and aprocessing system (403) configured to communicate with the communicationinterface (401), the pre-error memory (407), and the error log (409).The processing system (403) is further configured to capture the flowmeter output into the pre-error memory (407), with the flow meter outputoverwriting an oldest flow meter output stored in the pre-error memory(407), detect a predetermined start triggering condition in the flowmeter output, transfer a pre-error memory data from the pre-error memory(407) into the error log (409) when the predetermined start triggeringcondition is detected, and capture the flow meter output into the errorlog (409) after the predetermined start triggering condition isdetected.

A flow meter monitoring software product for monitoring a flow meter isprovided according to an embodiment of the invention. The softwareproduct comprises control software configured to direct a processingsystem to capture a flow meter output into a pre-error memory, with theflow meter output overwriting an oldest flow meter output stored in thepre-error memory, detect a predetermined start triggering condition inthe flow meter output, transfer a pre-error memory data into an errorlog when the predetermined start triggering condition is detected, andcapture the flow meter output in the error log after the predeterminedstart triggering condition is detected. The software product furthercomprises a storage system that stores the control software.

The following sets forth aspects of the invention. One aspect of theinvention comprises capturing the flow meter output in the error log fora predetermined time period after the predetermined start triggeringcondition is detected.

In another aspect of the invention, a predetermined end triggeringcondition is detected in the flow meter output and the capturing revertsto capturing the flow meter output into the pre-error memory after thepredetermined end triggering condition is detected.

In yet another aspect of the invention, hysteresis exists between thepredetermined start triggering condition and the predetermined endtriggering condition.

In yet another aspect of the invention, a meter identifier is stored inthe error log, with the meter identifier corresponding to andidentifying the flow meter generating the flow meter output.

In yet another aspect of the invention, an alarm condition is set whenthe predetermined start triggering condition is detected.

In yet another aspect of the invention, the flow meter comprises aCoriolis flow meter.

DESCRIPTION OF THE DRAWINGS

The same reference number represents the same element on all drawings.

FIG. 1 is a flowchart of a method of monitoring a flow meter accordingto an embodiment of the invention;

FIG. 2 is a graph of a representative flow meter output obtained from aflow meter;

FIG. 3 is a flowchart of a method of monitoring a flow meter accordingto another embodiment of the invention;

FIG. 4 is a block diagram of a flow meter monitoring system according toan embodiment of the invention; and

FIG. 5 is a block diagram of a pre-error memory according to anembodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1-5 and the following description depict specific examples of theinvention to teach those skilled in the art how to make and use the bestmode of the invention For the purpose of teaching inventive principles,some conventional aspects of the invention have been simplified oromitted. Those skilled in the art will appreciate variations from theseexamples that fall within the scope of the invention. Those skilled inthe art will appreciate that the features described below can becombined in various ways to form multiple variations of the invention.As a result, the invention is not limited to the specific examplesdescribed below, but only by the claims and their equivalents.

Flow Meter Monitoring Method—FIG. 1

FIG. 1 is a flowchart 100 of a method of monitoring a flow meteraccording to an embodiment of the invention. The method can be performedby a flow meter monitoring system 400, for example (see FIG. 4). In oneembodiment, the method monitors a Coriolis flow meter. However, itshould be understood that the method can monitor many types of flowmeters, including magnetic flow meters, vortex flow meters, andultrasonic flow meters, for example. The method can be used to monitorone or more flow meters, and is useful for not only detecting errorconditions in a flow through a flow meter but also for troubleshootingthe error condition and gathering data of flow meter operation leadingup to the error condition. This pre-error information is very usefulinformation for use in determining why the error condition happened.

In step 101, the flow meter output is captured to a pre-error memory.The flow meter output can include, among other things, a drive gain, adrive voltage, a drive frequency, a pickoff signals phase difference, atemperature of the material flowing through the flow meter, a tubeamplitude of the flow meter, a density value, a mass flow rate value, ameter identifier, a flow calibration factor, a zero value (delta timebetween pickoffs), etc.

The capturing continuously overwrites a newest flow meter output fromthe flow meter over an oldest flow meter output data stored in thepre-error memory. The capturing therefore captures and temporarilystores a window of data (see the pre-error time period 201 of FIG. 2 andthe accompanying discussion). This window of data can be permanentlystored upon the occurrence of an error in the flow meter output. Thepredetermined time period may be chosen in order to make capture ofpre-error data most likely. In this manner, the flow meter outputleading up to an error condition can be captured and saved, as will bediscussed further below.

In one embodiment, the pre-error memory comprises a circular buffer (seeFIG. 5 and the accompanying discussion). In another embodiment, thepre-error memory comprises a linked list. Other pre-error memoryconfigurations can be employed.

In step 102, the method compares the flow meter output to a starttriggering condition. An error condition exists if the flow meter outputexceeds the start triggering condition. The start triggering conditioncan include, for example, a drive gain error threshold, a phasedifference error threshold, a drive gain rate of change threshold, amass flow delta error threshold, a date/time, a number of occurrences ofa predetermined flow meter output value (i.e., three occurrences of anabnormal drive gain value, for example), or any desired error criterionor combination of error criteria.

The drive gain error threshold can comprise, for example, a drive gainamplitude threshold, a drive gain amplitude delta threshold, a drivegain frequency threshold, or a drive gain frequency delta threshold. Thephase difference error threshold can comprise, for example, a pickoffphase difference threshold or a pickoff phase difference delta threshold(i.e., an excessive or unexpected rate of change in phase betweenpickoff signals). It should be understood that the start triggeringcondition can comprise various combinations of any of the above errorconditions.

In one embodiment, a user of a flow meter monitoring system can chooseand set the start triggering condition, and the start triggeringcondition can be selected according to local conditions or know localerror propensities. If a start triggering condition is detected, themonitoring has detected an error condition in the flow meter output andthe method proceeds to step 103; otherwise, the method loops back tostep 101 until an error condition is detected.

In one embodiment, the start triggering condition is detected bycomparing the flow meter output to a comparison threshold. In anotherembodiment, the start triggering condition is detected by inputting theflow meter output into a bucket filter. The bucket filter separatessignals into discrete buckets, representing various signal levels. Thebucket filter generates an output for a particular bucket when apredetermined amount of bucket inputs are received in that bucket (i.e.,the bucket generates an output when the bucket overflows). In anotherembodiment, the start triggering condition is detected by inputting theflow meter output into a trending filter. The trending filter generatesa trend output that overlooks substantially one-time variations in theflow meter output, and generates an error signal if the flow meteroutput trends above the predetermined start triggering condition.

In step 103, the pre-error memory data captured to the pre-error memoryduring step 101 is transferred to an error log. The error log can bepre-existing or can be created in this step. In addition, the error logcan be located in a flow meter monitoring system performing the instantmethod, or can be external to the flow meter monitoring system. Forexample, the flow meter monitoring system 400 can transmit the pre- andpost-error data to a remote site, such as over the Internet, forexample. The error log can include other information, including otherflow meter data, such as an ambient temperature, a meter identifier,etc.

In step 104, the flow meter output is captured directly to the errorlog. Here, the error condition has occurred and post-error data is beingcaptured (see the post-error time period 202 of FIG. 2).

In additional actions, an alarm condition can be set and an errorindicator or error timestamp can be saved to the error log. Moreover,the flow meter monitoring system can use a historical data, such as anaverage mass flow rate and/or average density of the pre-error timeperiod 201, in substitution for the flow meter output.

In step 105, the method compares the flow meter output to an endtriggering condition. The error condition has ceased if the flow meteroutput is less than the end triggering condition. The end triggeringcondition can be, for example, a drive gain normal operation threshold(see FIG. 2), a phase difference normal operation threshold, a drivegain rate of change threshold, or any desired normal operationcriterion.

The drive gain normal threshold can comprise, for example, a drive gainamplitude threshold, a drive gain amplitude delta threshold, a drivegain frequency threshold, or a drive gain frequency delta threshold. Thephase difference normal threshold can comprise, for example, a pickoffphase difference threshold or a pickoff phase difference deltathreshold. It should be understood that the end triggering condition cancomprise various combinations of any of the above normal conditions.

In one embodiment, the user of the flow meter monitoring system canchoose and set the end triggering condition, and the end triggeringcondition can be selected according to local conditions or know localerror propensities. If an end triggering condition is detected, themonitoring has detected the termination of the error condition and themethod proceeds to step 106; otherwise, the method loops back to step104 until the end of the error condition is detected.

In step 106, the end of the error condition has been detected and themethod finalizes the error log. This can include storing additional datain the error log, such as a time stamp, inserting a meter identifierthat corresponds to and identifies the flow meter, etc. The error lognow includes both the pre-error data and a segment of post-error data.The size of the pre-error data is generally fixed, but the size of thepost-error data in this method embodiment depends on the duration of theerror condition.

In summary, this method embodiment continuously buffers the flow meteroutput until an error condition is detected, whereupon the buffer ofpre-error data is saved to an error log. The method also capturespost-error data to the error log until an end of the error condition isdetected

Flow Meter Output—FIG. 2

FIG. 2 is a graph of a representative flow meter output obtained from aflow meter. The flow meter output can represent a drive signal, a drivefrequency, a pickoff phase difference, etc. Two distinct time periodsare represented in the figure, a pre-error time period 201 and apost-error time period 202. A detected error condition causes atransition between the two time periods, and is detected according tothe error threshold 203. When the error condition is detected, the flowmeter monitoring switches to a post-error monitoring as represented bythe post-error time period 202. In one embodiment, when the flow meteroutput drops back below a normal threshold 204, the monitoring revertsto capturing the flow meter output in the pre-error memory 407.

It can be seen from the figure that in one embodiment the normalthreshold 204 and the error threshold 203 are chosen so as to includehysteresis, wherein the flow meter output must drop a predeterminedamount below the error threshold 203 before the flow meter output isjudged to be normal again. This prevents oscillating between error andnon-error states.

It can be seen from the figure that anomalies may exist in the signalleading up to the detection of the error condition (i.e., in thepre-error time period 201). This pre-error data may be very helpful andnecessary in diagnosing and/or understanding the flow meter output. Inaddition, the pre-error data can be useful for calibrating the flowmeter, for preventing future error conditions, etc. Moreover, thepost-error signal may also be useful for diagnosing and preventing errorconditions.

Meter Monitoring Method—FIG. 3

FIG. 3 is a flowchart 300 of a method of monitoring a flow meteraccording to another embodiment of the invention. In step 301, the flowmeter output is captured to a pre-error memory, as previously discussed.

In step 302, the method compares the flow meter output to the starttriggering condition, as previously discussed.

In step 303, the pre-error memory data captured during step 101 istransferred to an error log, as previously discussed.

In step 304, the flow meter output is captured directly to the errorlog, as previously discussed.

In step 305, the method checks to see if a predetermined monitoring timeperiod has expired. The predetermined monitoring time period can bemonitored by a timer, for example. In one embodiment, the user of theflow meter monitoring system can choose and/or set the predeterminedmonitoring time period, and the predetermined monitoring time period canbe set according to local conditions or know local error propensities.When the predetermined monitoring time period expires, the post-errormonitoring stops and the method proceeds to step 306; otherwise, themethod loops back to step 304 until the predetermined monitoring timeperiod expires. Consequently, the duration of the post-error time period202 is controlled by the predetermined monitoring time period.

Alternatively, this method embodiment could test for a number of memoryunits saved to the error log (409) (i.e., a post-error memory size), andcould stop saving the flow meter output to the error log (409) when asize limit is met. In another alternative, the method could apply bothan end triggering condition and a timer, and the post-error time period202 could be ended by either an end triggering condition or timerexpiration.

In step 306, the end of the error condition has been detected, and themethod finalizes the error log, as previously discussed.

In summary, this method embodiment continuously buffers the flow meteroutput until an error condition is detected, whereupon the buffer ofpre-error data is saved to an error log. The method captures post-errordata to the error log for a predetermined monitoring time period.

Flow Meter Monitoring System—FIG. 4

FIG. 4 is a block diagram of a flow meter monitoring system 400according to an embodiment of the invention. The flow meter monitoringsystem 400 can include a communication interface 401, a user interface402, and a processing system 403. The processing system 403 can includea memory 404 that includes a meter monitoring routine 405, a starttriggering condition 406, a pre-error memory 407, an end triggeringcondition 408, and an error log 409.

In operation, the flow meter monitoring system 400 receives flow meteroutput via the communication interface 401. The processing system 403performs the monitoring of the flow meter output and captures the flowmeter output to either the pre-error memory 407 or to the error log 409,depending on whether an error condition has been detected in the flowmeter output.

It should be understood that the flow meter monitoring system 400 canmonitor the flow meter outputs of one or more flow meters, including oneor more Coriolis flow meters. The flow meter monitoring system 400 cantherefore include multiple pre-error memories and multiple error logs.Only one pre-error memory and one error log are shown for the purpose ofclarity.

The communication interface 401 is any device capable of communicatingwith one or more flow meters. In addition, the communication interface401 can enable communications over telephone systems and/or digital datanetworks. Consequently, the flow meter monitoring system 400 cancommunicate with remote flow meters, remote memory media, and/or remoteusers.

The user interface 402 processes user inputs and outputs. The userinterface 402 allows users to set start triggering conditions and setend triggering conditions. In addition, the user interface 402 enablesusers to review captured data and perform other operations.

The user interface 402 can include an input portion that can comprise akeyboard or keypad, mouse, joystick or other pointing device, etc. Inaddition, the user interface 402 can include an output portion thatincludes a screen or other display. Alternatively, the user interface402 can comprise a touchscreen. In yet another alterative, the userinterface 402 can comprise a computer device in communication with theflow meter monitoring system 400.

The processing system 403 conducts operations of the flow metermonitoring system 400. The processing system 403 can comprise a generalpurpose computer, a microprocessing system, a logic circuit, or someother general purpose or customized processing device. The processingsystem 403 can be distributed among multiple processing devices. Theprocessing system 403 can include any manner of integral or independentelectronic storage medium, such as the memory system 404.

The meter monitoring routine 405, when executed by the processing system403, configures the processing system 403 to capture a flow meter outputinto the pre-error memory 407 (with the flow meter output overwriting anoldest flow meter output data in the pre-error memory 407), and detect apredetermined start triggering condition in the flow meter output. Whenthe predetermined start triggering condition is detected, the processingsystem 403 is configured to transfer a pre-error memory data into theerror log 409 and capture the flow meter output in the error log 409.

In one embodiment, the meter monitoring routine 405 comprises data andinstructions that are incorporated into a software platform, such asProLink II. ProLink is software for communicating with flow meters andlogging flow meter output, and is available from Micro Motion Inc. ofBoulder, Colo. ProLink is just one useful software platform, and themeter monitoring can be implemented in any suitable software language orplatform.

The start triggering condition 406 stores one or more start triggeringconditions that are used by the meter monitoring routine 405 todetermine when an error condition exists. The start triggering condition406 can include, for example, an error drive gain amplitude threshold,an error drive gain amplitude delta threshold, an error drive gainfrequency threshold, an error drive gain frequency delta threshold, anerror pickoff frequency phase difference threshold, an error pickoffphase difference delta threshold (i.e., an excessive or unexpected rateof change in phase between pickoff signals), etc., and can includevarious combinations of error conditions.

The pre-error memory 407 captures flow meter output when normaloperation of the flow meter is occurring. During the capturing, thepre-error memory 407 continuously receives a new flow meter output andoverwrites the new flow meter output over an oldest flow meter outputstored in the pre-error memory 407. The flow meter output is thereforecontinuously captured, and the amount of flow meter output stored in thepre-error memory 407 is determined by the size of the pre-error memory407. In one embodiment, a user can select a size of a pre-error memory407 for a particular flow meter, and can therefore designate how largeof a window of time of pre-error flow meter output is captured.

In one embodiment, the flow meter output is captured as digitized data.The amount of flow meter output in the pre-error memory 407 maytherefore be determined by not only the size of the pre-error memory 407but also by the type of digitization (i.e., by the sampling rate and thenumber of bits of resolution, for example).

The end triggering condition 408 stores one or more end triggeringconditions that are used by the meter monitoring routine 405 todetermine when a normal operation is present and/or when errorconditions cease to exist in the flow meter output. The end triggeringcondition 408 can include, for example, a normal drive gain amplitudethreshold, a normal drive gain amplitude delta threshold, a normal drivegain frequency threshold, a normal drive gain frequency delta threshold,a normal pickoff frequency phase difference threshold, a normal pickoffphase difference delta threshold (i.e., a normal or expected rate ofchange in phase between pickoff signals), etc., and can include variouscombinations of conditions.

The error log 409 receives the pre-error memory data from the pre-errormemory 407 when an error condition is detected (i.e., when theprocessing system 403 matches one or more start triggering conditions todata in the flow meter output). In addition, the flow meter output canbe captured to the error log 409 for a period of time after the errorcondition. In this manner, the error log 409 is used to store flow meteroutput occurring both before and after the error condition, andtherefore the error log 409 stores valuable data that can be used topredict, diagnose, and address error conditions in a flow meter.

The error log 409 can be a memory medium located in the flow metermonitoring system 400, or can be a remote memory medium. For example, ifthe error log 409 is a local memory medium, the error log 409 cancomprise a solid state memory, a magnetic memory, an optical memory,etc. Alternatively, the error log 409 can be located on a remote device,such as a remote database, wherein the flow meter monitoring system 400sends flow meter output to the error log 409 over a telephone line,wireless link, or computer network (such as the Internet, for example).

The flow meter monitoring system 400 can comprise a custom device.Alternatively, the flow meter monitoring system 400 can comprise ageneral purpose computer configured for flow meter output monitoring bysoftware.

Pre-Error Memory—FIG. 5

FIG. 5 is a block diagram of the pre-error memory 407 according to anembodiment of the invention. In this embodiment, the pre-error memory407 comprises a circular buffer, including a read/write pointer 501. Theread/write pointer 501 is used to substantially continuously write anewest flow meter output from the flow meter into the pre-error memory407, and is also used to read data out of the pre-error memory 407. Acircular buffer is one memory embodiment that accomplishes this goal.

In use, the read/write pointer 501 is incremented every time flow meteroutput is written to the pre-error memory 407. The pre-error memory 407can save the flow meter output as a byte or bytes of digital data, andthe read/write pointer 501 is incremented according to the size of theflow meter output data being saved. When an error condition is detected,the contents of the pre-error memory 407 are read out, starting at theread/write pointer 501 and ending at the memory location of theread/write pointer minus one memory unit (i.e., reading data D1-D8, inthat order).

Benefits of the Invention

Advantageously, the flow meter monitoring according to the inventionenables capture of flow meter output both before and after an errorcondition occurs. This enables the review of conditions and operation ofthe flow meter leading up to the error condition, as well as theconditions and operation of the flow meter after the error condition. Inaddition, the pre-error conditions can be compared to post-errorconditions. Moreover, the pre-error and post-error data can be used topredict errors, and can be used to calibrate, optimize, and/or adjustoperation of the flow meter.

The invention allows users to define various characteristics for datacollection, including collecting high and/or low threshold-based andtime-based event data to trigger upon, a number of occurrences of anevent to trigger upon, a data rate of change of events to trigger upon,specify data to collect before and after the triggered event(s) occur,and specify statistical functions to perform on data within the datacollection window. With this flexibility, the user can definecharacteristics of the flow meter output to be monitored, can collectonly the desired or needed data, and can collect specific data for apre-defined interval both before and after the conditions are met.

1. A method of monitoring a flow meter, the method comprising the stepsof: capturing a flow meter output into a pre-error memory, with the flowmeter output overwriting an oldest flow meter output stored in thepre-error memory; detecting a predetermined start triggering conditionin the flow meter output; transferring a pre-error memory data into anerror log when the predetermined start triggering condition is detected;and capturing the flow meter output in the error log after thepredetermined start triggering condition is detected.
 2. The method ofclaim 1, further comprising a preliminary step of accepting a user inputthat configures the predetermined start triggering condition.
 3. Themethod of claim 1, with the capturing comprising capturing the flowmeter output in the error log for a predetermined time period after thepredetermined start triggering condition is detected.
 4. The method ofclaim 1, further comprising the subsequent steps of: detecting apredetermined end triggering condition in the flow meter output; andreverting to capturing the flow meter output into the pre-error memoryafter the predetermined end triggering condition is detected.
 5. Themethod of claim 4, further comprising a preliminary step of accepting auser input that configures the predetermined end triggering condition.6. The method of claim 4, wherein hysteresis exists between thepredetermined start triggering condition and the predetermined endtriggering condition.
 7. The method of claim 1, further comprisingstoring a meter identifier in the error log, with the meter identifiercorresponding to and identifying the flow meter generating the flowmeter output.
 8. The method of claim 1, with the flow meter comprising aCoriolis flow meter.
 9. A flow meter monitoring system (400) comprising:a communication interface (401) configured to receive flow meter output;a pre-error memory (407); an error log (409); and a processing system(403) configured to communicate with the communication interface (401),the pre-error memory (407), and the error log (409), capture the flowmeter output into the pre-error memory (407), with the flow meter outputoverwriting an oldest flow meter output stored in the pre-error memory(407), detect a predetermined start triggering condition in the flowmeter output, transfer a pre-error memory data from the pre-error memory(407) into the error log (409) when the predetermined start triggeringcondition is detected, and capture the flow meter output into the errorlog (409) after the predetermined start triggering condition isdetected.
 10. The flow meter monitoring system (400) of claim 9, whereinthe predetermined start triggering condition (406) is stored in a memory(404) of the flow meter monitoring system (400).
 11. The flow metermonitoring system (400) of claim 9, wherein the pre-error memory (407)is stored in a memory (404) of the flow meter monitoring system (400).12. The flow meter monitoring system (400) of claim 9, wherein the errorlog (409) is stored in a memory (404) of the flow meter monitoringsystem (400).
 13. The flow meter monitoring system (400) of claim 9,wherein the error log (409) is stored external to the flow metermonitoring system (400).
 14. The flow meter monitoring system (400) ofclaim 9, wherein the predetermined start triggering condition isuser-settable.
 15. The flow meter monitoring system (400) of claim 9,wherein the processing system (403) is further configured to capture theflow meter output in the error log (409) for a predetermined time periodafter the predetermined start triggering condition is detected
 16. Theflow meter monitoring system (400) of claim 9, wherein the processingsystem (403) is further configured to detect a predetermined endtriggering condition in the meter output and revert to capturing theflow meter output into the pre-error memory (407) after thepredetermined start triggering condition is detected.
 17. The flow metermonitoring system (400) of claim 16, wherein the predetermined endtriggering condition is user-settable.
 18. The flow meter monitoringsystem (400) of claim 16, wherein hysteresis exists between thepredetermined start triggering condition and the predetermined endtriggering condition.
 19. The flow meter monitoring system (400) ofclaim 9, with the flow meter monitoring system (400) being configured tomonitor a Coriolis flow meter.
 20. A flow meter monitoring softwareproduct for monitoring a flow meter, the software product comprising:control software configured to direct a processing system to capture aflow meter output into a pre-error memory, with the flow meter outputoverwriting an oldest flow meter output stored in the pre-error memory,detect a predetermined start triggering condition in the flow meteroutput, transfer a pre-error memory data into an error log when thepredetermined start triggering condition is detected, and capture theflow meter output in the error log after the predetermined starttriggering condition is detected; and a storage system that stores thecontrol software.